Why We Get Car Sick
In this short video, the folks at Head Squeeze explain why we get car sick (and sea sick, and motion sickness in general). While the explanation is interesting, the most useful bit may be the tip about moving farther forward in the vehicle—I have several relatives who can survive a front-seat ride but simply won't make it in the back. Have a look:
See also: Why People Vomit (it's an article, not a video—you're welcome).